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Creating a global Whois class

, 6 Dec 2003
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Lookup a domain name for any tld (top level domain)


I realise there is already a Whois example for C# on codeproject, in the form of an snippet. The class I've posted here encapsulates a little more functionality than that example, and is taken from a Perl script i wrote a few years back.


The Whois class has one main method, Lookup(domain). From this, the class works out what whois server should be used for the domain lookup. This is done by a trick taken from the Perl script, the service is provided by, hosted by CenterGate. From performing a dns lookup on the domain name's tld (e.g. .com for, attached to, you're provided with the address of the whois server for that domain, if one exists.

I've built into the class, the ability to provide your own whois server, via the WhoisServer property. I've also added checks for a few domain names which don't provide free whois servers, and the .tk domain which does, but isn't on the service.

The class performs the lookup, and raises an event, LookupComplete when it's finished, passing a WhoisEventArgs class with it, which provides the results of the lookup, and the whois server that was used.

To check whether a domain is taken or not, is up to you - you'll have to parse the string provided in the WhoisInfo property of the WhoisEventArgs class.

The example project is a small windows forms application, to demonstrate how to use the class. The class doesn't cater for non-resolving whois servers at present, it could perhaps do with a few more lines of error trapping in this area.


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About the Author

Web Developer
United Kingdom United Kingdom
London based C# programmer.
I maintain my own pet C# site in my spare time.

Comments and Discussions

QuestionHow to fix occational timeouts Pinmemberthorssig5-Oct-13 9:52 
Questionvery bad code | code kuy kuy PinmemberSuchart_mart6-Feb-12 23:30 
GeneralSocket Exception Unhandled - No such host known PinmemberSniper16718-Jul-07 19:36 
GeneralRe: Socket Exception Unhandled - No such host known Pinmembersmallguy7823-Jul-07 1:10 
GeneralWhois class implementation PinmemberSyst3m Crash3r 48030-May-06 7:27 
GeneralRe: Whois class implementation Pinmembersmallguy7814-Nov-06 1:16 
QuestionC# IPHostEntry Cache??? Pinmemberkvnsdr20-Aug-04 18:56 
Very impressive indeed.
I code for fun and would like some advice on the IPHostEnty class.
Here is one of the coolest few lines of code to perform a NSLookUp. Simply enter an IP in textBox1, click a button and the domain name translates in textBox2 (providing your workstation is on a WAN.
Q. How could we build a 'cache' to capture redundant IP's/Domain's to add lookup performance???
Q. How could we add our own know IP's/Domain's to this 'cache' ??? (Because NOT every IP will resolve)
Preferably the code would check our personal 'cache' first before looking on the Internet or elsewhere.....
public void ButtonLookupDomain_Click(object sender, EventArgs ea)
IPHostEntry IP = Dns.Resolve(textBox1.Text);
txtBox2.Text = IP.HostName;

GeneralWhois Server Pinmemberyoussef elmansouri9-Dec-03 0:25 
GeneralRe: Whois Server Pinmembersmallguy789-Dec-03 8:18 

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